Mass spectrometer

Abstract

A rotating field mass spectrometer includes an ionizing structure having a pair of conductive electrodes located closer to one another than the mean free path of the gas being ionized, and a rotating field mass spectrometer part for analyzing ions produced by the ionizing structure. The membrane may include a supporting portion, and a relatively thin non-supporting portion where the ions are formed.

1. A rotating field mass spectrometer system, comprising:
 an ionizing structure, comprising a substrate having at least one opening, a first conductive electrode extending on a first surface of the substrate and a second conductive electrode extending on a second surface of the substrate, and a separator insulating element, having a thickness less than 1 micron, separating said first and second conductive electrodes at said at least one opening, said first and second conductive electrodes being separated by a width of said insulator at said opening; and  
 a rotating field mass spectrometer part that receives ions from said ionizing structure and which characterizes said ions.  
 
     
     
       2. A rotating field mass spectrometer system as in  claim 1 , wherein said first and second conductive electrodes are separated by less than 300 nm at said at least one opening. 
     
     
       3. A rotating field mass spectrometer system as in  claim 1 , wherein said separator insulating element is a dielectric. 
     
     
       4. A rotating field mass spectrometer system as in  claim 3 , wherein said separator insulating element is formed of silicon nitride. 
     
     
       5. A rotating field mass spectrometer system as in  claim 1 , wherein said first and second electrodes are formed of one of gold, chrome or titanium. 
     
     
       6. A rotating field mass spectrometer system as in  claim 1 , wherein said mass spectrometer system operates at substantially ambient pressure. 
     
     
       7. A rotating field mass spectrometer system as in  claim 6 , wherein said mass spectrometer system includes a solid-state electrode sensor array that detects ions. 
     
     
       8. A rotating field mass spectrometer system as in  claim 1 , wherein there are plurality of said thin portions, and said thin portions each formed from first and second conductive electrodes which are separated by said less than 1 micron. 
     
     
       9. A rotating field mass spectrometer system as in  claim 1 , wherein said first and second conductive electrodes are separated by less than a mean free path of a gas being analyzed. 
     
     
       10. A rotating field mass spectrometer system, comprising:
 an ionizing structure formed of a thick supporting portion with holes formed in the thick supporting portion and having first and second metal electrodes coated on surfaces of the thick supporting portion extending into the holes in the thick supporting portion, where a distance between the first and second metal electrodes within the holes of the thick supporting portion is less than the mean free path of a material being ionized; and  
 a rotating field mass spectrometer part, receiving ions formed by said ionizing structure.  
 
     
     
       11. A method of forming a rotating field mass spectrometer, comprising:
 forming a layer of thin dielectric material on a substrate that has a first specified thickness of a sufficient thickness to maintain structural integrity;  
 forming a first electrode on the first surface of said thin dielectric material, said first electrode being formed of a metal material;  
 back etching at least one hole in said substrate;  
 forming a second electrode on a second surface of the substrate including the at least one back etching holes, such that at least a portion of the second electrode is on a second surface of the thin dielectric material;  
 forming holes in the second electrode, thin dielectric material and the first electrode, which holes have side surfaces where the first and second electrodes are separated by a width of the thin dielectric material; and  
 forming a rotating field mass spectrometer part to receive ions which have passed through said holes.  
 
     
     
       12. A method as in  claim 11 , wherein said thin dielectric material has a thickness which is less than the mean free path of the gas intended to be ionized by the ionizing structure. 
     
     
       13. A method as in  claim 11 , wherein said forming electrodes comprises depositing gold. 
     
     
       14. A method as in  claim 13 , wherein said forming a thin dielectric comprises depositing silicon nitride. 
     
     
       15. A method as in  claim 11 , wherein said thin dielectric has a thickness less than 500 nm. 
     
     
       16. A method as in  claim 11 , wherein said thin dielectric has a thickness less than 300 nm. 
     
     
       17. A method as in  claim 16 , further comprising applying a voltage less than 15 volts between said first and second electrodes to form a field between said first and second electrodes in the range of megavolts per meter. 
     
     
       18. A method as in  claim 11 , wherein said detecting comprises using a pixelated electrometer array to detect said ions. 
     
     
       19. A rotating field mass spectrometer, comprising:
 an ionizing structure, having supporting portions, and unsupported parts between said supporting portions, where said unsupported parts include electrodes which are separated by a distance less than the mean free path of a specified sample, and include holes that pass through the ionizing structure; and  
 a rotating field mass spectrometer part, receiving ions from said ionizing structure, and determining characteristics of the ions.  
 
     
     
       20. A rotating field mass spectrometer system, comprising:
 an ionizing structure, comprising a substrate having at least one opening, a first conductive electrode extending on a first surface of the substrate and a second conductive electrode extending on a second surface of the substrate, and a separator insulating element, having a thickness less than 1 micron, separating said first and second conductive electrodes at said at least one opening, said first and second conductive electrodes being separated by a width of said insulator at said opening; and  
 a rotating field mass spectrometer part that receives ions from said ionizing structure and which characterizes said ions;  
 wherein said separator insulating element is a dielectric having dielectric breakdown of at least 10 7  volts/meter.  
 
     
     
       21. A rotating field mass spectrometer system as in  claim 20 , wherein said separator insulating element has a dielectric breakdown of between 10 8  and 10 9  volts/meter. 
     
     
       22. A method of forming a rotating field mass spectrometer, comprising:
 depositing a layer of thin dielectric material having a dielectric breakdown of at least 10 7  volts/meter on a substrate that has a first specified thickness of a sufficient thickness to maintain structural integrity;  
 forming a first electrode on the first surface of said thin dielectric material, said first electrode being formed of a metal material;  
 back etching at least one hole in said substrate;  
 forming a second electrode on a second surface of the substrate including the at least one back etching holes, such that at least a portion of the second electrode is on a second surface of the thin dielectric material;  
 forming holes in the second electrode, thin dielectric material and the first electrode, which holes have side surfaces where the first and second electrodes are separated by a width of the thin dielectric material; and  
 forming a rotating field mass spectrometer part to receive ions which have passed through said holes.  
 
     
     
       23. A method of forming a rotating field mass spectrometer, comprising:
 depositing a layer of thin dielectric material having a dielectric breakdown of between 10 8  and 10 9  volts/meter on a substrate that has a first specified thickness of a sufficient thickness to maintain structural integrity;  
 forming a first electrode on the first surface of said thin dielectric material, said first electrode being formed of a metal material;  
 back etching at least one hole in said substrate;  
 forming a second electrode on a second surface of the substrate including the at least one back etching holes, such that at least a portion of the second electrode is on a second surface of the thin dielectric material;  
 forming holes in the second electrode, thin dielectric material and the first electrode, which holes have side surfaces where the first and second electrodes are separated by a width of the thin dielectric material; and  
 forming a rotating filed mass spectrometer part to receive ions which have passed through said holes.